MIT’s new device to harvest water from desert

Researchers from the Massachusetts Institute of Technology (MIT) has unveiled a new device that is expected to get drinkable water out from the driest areas of deserts

The system is based on relatively new high-surface-area materials called metal-organic frameworks (MOFs).

The currently available fog-harvesting methods require higher levels of 100 per cent humidity in the air and the dew-harvesting refrigeration-based systems require 50 per cent humidity. Both the existing methods also require high amounts of energy for cooling. According to MIT researchers, the new system extracts drinking water from very dry places in the desert air with relative humidities even as low as 10 per cent.

The new system is field-tested on a rooftop in the dry air of Tempe, Arizona. The test device was powered solely by sunlight. The researchers said that although it was a small proof-of-concept device, once scaled up, its output is set to be equivalent to more than a quarter-litre of water per day per kilogram of MOF.

The device is based on a concept that MIT team proposed in a science paper in 2016 and is published in the journal Nature Communications. Evelyn Wang, the Gail E. Kendall Professor in the Department of Mechanical Engineering, was the senior author of both papers. Sameer Rao, MIT postdoc, and former graduate student Hyunho Kim, along with others at MIT and the University of California at Berkeley were the lead authors of the latest paper.

With an optimal material choice, the output is expected to be three times higher than that of the current version, said Kim.

Apart from working at lower humidities, the new system also avoids the need for pumps and compressors that can wear out, noted the researchers. “The device can be operated in a completely passive manner, in places with low humidity but large amounts of sunlight,” said Rao.

The MIT team has tested the water produced by the system and said that no traces of impurities have been found, thus confirming the harvest of high-quality water.